Answer: (-2, 0)
Step-by-step explanation
Add up the x coordinates and divide in half
(-3 + (-1) )/2 = -4/2 = -2
The x coordinate of the midpoint is x = -2
Do the same for the y coordinates also.
(1 + (-1) )/2 = 0/2 = 0
The y coordinate of the midpoint is y = 0.
The midpoint is located at (-2,0) which is indicated in the graph your teacher gave you. This midpoint is on segment AB and also on the x axis.